This invention relates to the radiation of electromagnetic power from an assembly of horn radiators operating at different frequency bands and, more particularly, to an assembly of horn radiators wherein a radiator operating at a higher frequency operation is nested within a radiator operating at a lower frequency of radiation.
In communication systems, such as in systems employing a satellite for the communication of signals to various parts of the earth, it is common practice to employ an antenna system comprising a reflector and an array of radiators positioned for illuminating the reflector. Such an antenna system is well suited for the generation of a fan beam which can be directed to a geographical section of the earth. As an example of the construction of such an antenna system, it is common practice to construct the radiators in the form of horn radiators. Signals transmitted by the antenna system may be in one frequency band, while signals received by the antenna system may be in a different frequency band.
A situation of particular interest involves the generation of a spot beam in a high frequency band concurrently with the generation of a broad beam at a low frequency band. While it has been the practice, in many situations, to use a separate set of radiators and separate reflectors for generation of beams at high and at low frequency bands, in the present situation of interest, it is desired to locate the radiator of the spot beam concentric with a radiator of the low frequency band, and to use the same reflector for both the beams of the high and the low frequency radiations.
A problem arises in the colocating of a high frequency horn radiator with a low frequency horn radiator in that one of the horns may provide blockage of the other horn, or may otherwise interfere with the radiation characteristics of the other horn. Thus, in the foregoing situation of interest, there is a requirement to illuminate a single reflector with radiations at two different frequency bands from two radiators which are colocated. However, heretofore, no satisfactory antenna system for horn radiators has been available.